In the past, my home lakes here in Southern California were fairly deep impoundments and fall turnover was an easy enough thing to see happening and adjust to.  However, for the past few years, the main lake I have fished is nothing like those lakes and I am not sure if I know when this turnover is happening.

 

The lake is a shallow (11 ft. at the deepest) development lake, void of nearly any vegetation with about 2 dozen aerators placed throughout it.  It is an electric motor only lake, but during nice days, there is a bit of boat traffic (people cruising in pontoon boats) that keeps the water stirred up and adds to the oxygenation.  During the height of summer, the water surface temperature will top out near 85 degrees while the coldest I have seen it in January is 55 degrees.  While our air temps can range from 100+ in the summer to mid 30's in the winter, the Pacific Ocean has a real moderating effect on the area so we don't get a lot of variance.  Typical wind pattern is calm during the mornings with a 3-8 mph onshore breeze in the afternoons.

 

Two weeks ago, the surface water temperature dropped from 72 to 67 in a week, even though we had sunny days with highs in the 80's & lows in the mid 50's (no storms) all week.  The visibility dropped from about 4 feet to about 2 feet.  Last week, we had cooler, overcast days for most of the week with rain one evening, but the surface temperature was still at 67 as of yesterday.  The water had cleared up a little, but was still murkier than normal. 

 

Fishing wise, the bass made an abrupt change the week the temperature fell 5 degrees.  The only active fish I found were on deep structure.  Yesterday, the fish seemed to be in a post frontal condition.  I found them in many normal shallow locations, but they were backed up into  the darkest spots available and only biting if I was able to put a lure right on their nose.  Only at the end of the day was I able to catch anything on a lure they had to chase (jerkbait), everything else was on jigs & plastics.

 

I am assuming this is the typical two week funk that fish go through in a fall turnover, but am thrown a little by the differences that a shallow lake has in turning over compared to a more traditional impoundment.  This lake is probably more similar to a Florida natural lake (without the vegetation obviously) and I have never experienced what those lakes go through in the fall. 

 

Has anyone else had experiences with shallow lakes turning over?

First you should know that not all lakes turn over or stratify.

The difination of a turnover is the lower layers of water rise to the surface or turnover.

The easiest way to know is by the sulfur odor and chunks of bottom debris on the surface. More difficult is using a temperature probe to identify if warmer and colder water layers exist before the cold weather cools the water surface. If you have a boat with good sonar you can tune the return signal to indicate where the warmer and colder more dense water layers depth is located.

Tom

That is what perplexed me. There was no rotten egg smell, in fact no out of the ordinary smells. There was more debris on the surface than usual, but I wasn't sure if that was from the bottom of the lake or from the dying leaves of fall & an increase of waterfowl on the lake.

Can lakes have some kind of water flipping or mixing without it being a full on turnover?

That is what perplexed me. There was no rotten egg smell, in fact no out of the ordinary smells. There was more debris on the surface than usual, but I wasn't sure if that was from the bottom of the lake or from the dying leaves of fall & an increase of waterfowl on the lake.

Can lakes have some kind of water flipping or mixing without it being a full on turnover?

I have no proof of this but I believe there is. Most of our lakes are shallow and never develop a thermacline but we get the nasty chunks of stuff floating on the surface when those lakes start to cool off and about a week of very difficult fishing before that stuff disappears and fishing improves. Even without a normal turnover the bottom of the lake is still going to be cooler and the top is warmer so when the surface begins to cool there must be some kind of water mixing that releases all the junk from the bottom of the lake. 

Fall turnover to me is crystal clear water no signs of life on shore and bronchitis